Engine systems generally include an Exhaust Gas Recirculation (EGR) system associated therewith. The EGR system is configured to reduce NOx generation and increase efficiency of the engine system by recirculating a part of the exhaust gases to an air intake system of an engine. The recirculated exhaust gases are generally introduced into an intake plenum of the air intake system and are mixed with non-combusted intake air therewithin.
An EGR cooler is associated with the EGR system for cooling the recirculated exhaust gases. The EGR coolers have a common problem of fouling i.e. deposition of hydrocarbon (HC), soot, etc. on a gas side of the EGR cooler. The depositions result in loss of heat transfer capability as the depositions are highly non-conductive, thereby reducing efficiency of the EGR cooler. Further, the loss in heat transfer capability increases harmful emissions like NOx in the exhaust gases. The depositions also increase pressure drop across a flow of the recirculated exhaust gases through the EGR system. The increase in pressure drop in turn increases the back pressure on the engine, thereby increasing fuel consumption and particulate matter emissions.
U.S. Pat. No. 7,299,793 describes a compression ignition engine having an EGR loop that contains a metallic DOC for treating recirculated exhaust gas obtained directly from cylinder exhaust through an exhaust manifold before the exhaust gas passes through a cooler, and an EGR valve to an intake system.